Isotropic charged cosmologies in infrared-modified electrodynamics.

Abstract

It has long been known that the covariant formulation of quantum electrodynamics conflicts with the local description of states in the charged sector. Some of the solutions to this problem amount to modifications of the subsidiary conditions below some arbitrarily low photon frequency. Such infraredmodified theories have been shown to lead to Maxwell equations modified with an additional classical electromagnetic current induced by the quantum charges. The induced current only has support for very small frequencies and cancels the effects of the physical charges on large scales. In this work, we explore the possibility that this deelectrification effect could allow for the existence of isotropic charged cosmologies, thus evading the stringent limits on the electric charge asymmetry of the Universe. We consider a simple model of infrared-modified scalar electrodynamics in the cosmological context and find that the charged sector generates a new contribution to the energy-momentum tensor of which the dominant contribution at late times is a cosmological constantlike term. If the charge asymmetry was generated during inflation, the limits on the asymmetry parameter in this model in order not to produce a too-large cosmological constant are very stringent eta(Q) < 10(-131)-10(-144) for a number of e-folds N = 50-60 in typical models. However, if the charge imbalance is produced after inflation, the limits are relaxed in such a way that eta(Q) < 10(-43) (100 GeV/T-Q), with T-Q the temperature at which the asymmetry was generated. If the charge asymmetry has ever existed and the associated electromagnetic fields vanish in the asymptotic future, the limit can be further reduced to eta(Q) < 10(-28).